Abstract: With the stress-factors affecting the stability of tunnel-surrounding rock, based on the stress distribution of deep tunnel-surrounding rock and the principle of stress relief method, the in-situ stress measurement of repeatedly stress relief on the original boreholes was approached, and the scientific basis of discriminating the original boreholes was established. According to the measurement of basic borehole and checking borehole, the relations between the original rock stress in other measuring area and radius of the tunnel could be deduced. The project practice showed that, in Kongzhuang colliery, Datun coal mining area with buried depth more than 1 000 m, the basic borehole enter the original rock stress area at the distance about 3.7R, the original vertical stress result is 23.3 MPa，which was proved in the checking borehole and extension borehole.

Key words: in-situ stress, stress relief, the original boreholes, measurement method, criterion